What speed are you looking for? Are you meaning a maximum sample rate? I think the "HS" may be capable of a higher rate but the unit has to be able to compute those samples faster to make use of it. I doubt you will be able to get better performance than your GRP. The Heading sensor (digital compass) will keep your boat icon pointed at slow speeds with less lag than just the GPS heading. That is the only advantage you will get. It is your $130 you will have to decide if it is worth it to you and your fishing style. Bob